Control of color television systems of the cathode ray tube type



y 1950 w. J. OESTREICHER 2,938,142

CONTROL. OF COLOR TELEVISION SYSTEMS OF THE CATHODE RAY TUBE TYPE FiledApril 1, 1955 F I65 F I65 LOCAL REFERENCE sc(3.5esmc) I SHEET BEAM 1480oTO D,

6%; 2 45 15 go i I r- 7 5'4 wnn'z BALANCE J 4: RL :3 V -n- [T TO Dz (29)f/ l 3% 47 UNDEMODULATEP CHROMA SIGNAL APERTURE NA5K4 3 a a I FOCUS E An I a p, 38 3s 3 A I k ..:\3 i ,aa 2 8 D3, 3 A ACCELER- g 8 \lNlVOl-T 5AqE F OEFLECTION 3 i 41 vows A B'Pos i ELEMENTS UNDEMOD.

* cmiomuauc: W 6

slquAL BHIGHTNESS mam. 12 A To D1 DEHODULATORS 63- M134 EP D H COL OR K1 H-f SELECTION UNDEMOO. 'l 2, WHITE BALANCE PLATES IN cHRonA 2M GUNINPUT To Da CHROMA VIDEO AMP INVENTOR.

WARREN J'.oEsTRE|cHE TO LOCAL osc (3.56 mc) CONTROL OF COLOR TELEVISIONSYSTEMS OF THE CATHODE RAY TUBE TYPE Warren J. Oestreicher, Flushing,N.Y., assignor to Kendon Electronics, Inc., a corporation of New YorkFiled Apr. 1, 1955, Ser. No. 498,710

2 Claims. -(Cl. 815-26) This invention relates to cathode ray apparatusfor color television and more specifically to a reproduction system ofthe aperture mask type.

One of. the objects of this invention is to reproduce two or more colorsfrom a corresponding number of phosphor elements or strips by displacingthe electron beam under control of color information signals so as tomove the image produced by the apertures of the mask on the phosphorelements about axes formed by the separation lines between adjacentphosphor elements.

Another object of the invention is to apply color and intensityinformation signals to separate electrodes.

Still another object of the invention is to displace the axis of theelectron beam under control of color information signals so as toproduce a displaced beam intersecting the 'undisplaced beam at theaperture mask.

A further object of the invention is to adjust the white balance byadjusting the rest position of the shadows produced by the-.maskapertures on the separation lines be tween adjacent phosphor elements.

These and other objects of the invention will be more fully understoodfrom the drawings enclosed herewith in which Fig. 1 represents anarrangement of aperture mask and phosphor elements as actuated by anelectron beam in accordance with this invention.

Figs. 2 and 3 represent a modification of Fig. 1.

Fig. 4 represents a circuit for operating an arrangement of the aperturemask type such as shown in Fig. 1 in accordance with certain principlesof the invention.

Figs. 5 and 6 represent a portion of the circuit of Fig. 4 in greaterdetail.

Fig. 6 represents a modification of Fig. 5.

In Fig. 1 there are schematically indicated at 1, 2, 3, 4, a number ofadjacent phosphor elements representing in cross-section two verticalstrips of phosphor materials capable of reproducing respectively underthe impact of electrons substantially complementary colors sufficient tocover at least an important portion of the visible spectral range.

These phosphor strips are reproduced on the inner face 5 of a cathoderay tube by means of screen-printing or any other means as is well knownin the art of manufacture of cathode ray tubes.

In front of phosphor strips 1, 2, 3, 4, etc., and at a predetermineddistance therefrom, there is arranged an aperture mask 6 having openingsor apertures 8, 8 aligned with phosphor strips 1, 2 and 3, 4,respectively, in such a manner that an electron beam 9 derived, forexample, from a single electron gun 10 is capable of projecting orfocusinga picture of an aperture as, for example, indicated in Fig. 1 at7, on two adjacent phosphor elements of complementary colorcharacteristics as, for example, indicated in Fig. 1 at 1 and 2. Theimage thus produced 2,938,142 Patented May 24, 1960 by electron beam 9over separation line between adjacent elements 1 and 2 is indicated inFig. 1 by dotted line 11.

In accordance with one feature of this invention, as explained ingreater detail in my copending patent application, Serial No. 495,953,filed March 22, 1955, electron beam 9 under control of correspondingcolor information signals is caused to deviate in one direction oranother as indicated in Fig. 1 by arrows 12, 13 respectively and thenreconverged so as to approach aperture mask (6) from varying angles,thereby causing reproduction of predetermined color hues controlled bydifferent but predetermined proportions of phosphor strips whichcontribute depending upon the displacements of the electron imagediiferent areas and therefore different amounts of fundamental colors tothe difierent color hues.

The white balance of this color system is determined by the zero or restposition of image 11 produced by electron beam 9 with respect to theseparation line between adjacent phosphor strips.

Adjustment of this zero position therefore can be used to adjust thewhite balance of the color system used in accordance with thisinvention.

While Fig. 1 shows the invention in cross-sectional view, as applied toa two-color system, Fig. 2 shows in front elevation, a three-colorphosphor screenelement where the arrays of adjacent longitudinal stripsof phosphor elements of Fig. l are replaced by triplets of phosphor dotsor segments arranged in the circular manner approximately indicated inFig. 2 at 14, 15 and 16 forming the sectors of an approximate circulararea indicated schematically by line 17. In this case the aperture maskhas circular openings and the image cast by the electron beam onphosphor elements 14, 15 and 16 has in its zero or rest position thecircular shape schematically indicated in Fig. 2 at 18.

In this case, however, instead of a lateral deflection in one directiononly a multi-directional type of deflection is used to reproduce colorhues determined by ditferent proportions of color segments 14, 15, 16covered by the electron image 18 cast by the mask apertures.

In order to achieve this result, in addition to a lateral movementindicated by arrows 12, 13 the electron beam and the corresponding image18 is caused to execute a perpendicular movement as indicatedperpendicular to arrows 12, 13 under control of corresponding circuitsand color component information and color selection defiection platessimilar to those shown with respect to Fig. 1 and a two-colorreproduction system.

Fig. 3 shows the invention as applied to a two-color system which issomewhat improved in color rendering by the addition of a third colorstrip of well-defined dimension and structure, or by subdivision of oneof the twocolor strips shown in Fig. 1 into two strips, or by replacingthe color separation line between adjacent color strips, by a thirdcolor strip of predetermined width and structure as indicated forexample in Fig. 3 by arranging an orange color strip 19 between cyan andmagenta color strips 20, 21 with the mask image being indicated at 22 inan operating position depending upon the position of the electron beam.

In this case, as well as in the case of two-color reproduction, thewhite balance can be adjusted in accordance with the invention byadjusting the zero rest position of the electron image 18 on colorsegments 14, 15, 16.

In Fig. 4 an apparatus is illustrated to operate a tele-. vision systemsuch as shown in Fig. 1.

The various elements of the color reproducer are only shown as far asthey have any bearing on the invention.

The standard color signals derived from a transmitter and received atthe receiver antenna, after corresponding amplification and separationare divided into hue and luminance Signals in otherwise well knownmanner.

The hue signals are demodulated at 23 in a manner also otherwise wellknown or as indicated in greater de tail in Figs. and 6,'and separatedinto orange-red video signals at 24 and into cyan video signals at 25.

The outputs of stages 24 and 25 are respectively applied over lines 26,27 to opposite deflection plates 23, 29 of cathode ray tube 30 causingthe displacement of the axis of electron beam 31 derived from gun 32 inaccordance with the invention, so as to cause movement of the electronpicture image produced by openings 33 of aperture mask 34 ofotherwise-well-kno-wn structure or of a structure such as disclosed inthe above-mentioned copending patent application, on the adjacent pairsof At the same time electron beam 31 is caused to be periodicallydeviated with the aid of perpendicular electromagnetic deflection coilsor systems 38,39 under control of synchronizing signals in otherwiseWell known manner to efiect scanning of screen 37 as is well known inthe art of operation ofcathode ray tubes.

Luminanceinformation is derived from amplifier 40 and applied over line-41 to grid, 42 of cathode ray tube 30, so as to effect simultaneouslywith the changes in color hue the appropriate changes in intensity.

Electron beam 31 is produced in otherwise well known manner by a singlecathode 41 which focuses electron beam 31 on screen 37. I

In accordance with this invention electrostatic deflection plates 28, 29are arranged concentric with respect to the axis or cathode ray tube 30so as to produce a beam intersecting the axis of the beam when it is notdisplaced; this intersection will occur at a point substantially at ornear aperture mask 34. i I

Electrostatic deflecting plates 28, 29 may be replaced by 7 otherdeflecting means such as electromagnetic deflecting coils withoutdeparting from the scope of the invention.

Further in accordance with the invention the white balance of the colorsystem depends on the bias voltage applied to at least one ofdisplacement plates 28, 29 or as indicated in Fig. 4 betweendisplacement plates 28, 29. This bias is derived from a potentiometer43, adjustment of which will adjust the white balance in accordance withthe invention.

This balance may also be effected by a magnetic field appliedtransversely in the vicinity of plates 28, 29 by,

means of an external electroor permanent magnet struc-.

' ture, 28', 29.

A demodulation circuit such as shown in Fig. 4 at 23 isdescribed indetail in Fig. 5, involving a single tube 44 of the sheet beam orbeam-sharing type in which electron beam. 45 after modulation is sharedby two or more anodes 46, 47 under control of deflecting electrodes 43,49 to which an appropriate source of synchronous reference signals isapplied.

Thus the same electrode structure serves simultaneously to perform thefunction of synchronous demodulation and amplification in separatechannels 50, 51 which are connected'respectively to color selectiondeflecting plates 28, 29.

The varying electron current derived from beam 45 is used to produce avarying voltage across load" resistors 52, 53 and across a portion ofwhite balance potentiometer 54, which also establishes the relativelystatic direct current potential of anodes 46, 47 and deflectingelectrodes 28, 29.

In the modification of Fig. 6 separate demodulation and amplificationcircuitstare shown.

In Fig. 6 the diodes 55', 56 which may be of germanium, silicon orvacuum type, are excited by the reference oscillator circuit 57 indegrees phase displacement. Diodes 55, 56 therefore conduct for somepart of the cycle, preferably over 5 or 10 degrees, and are biasedthrough resistors SS, 59 to nonconduction for the remainder of thecycle.

The chroma signal therefore appears during this interval (of say 5degrees) across the 10,000 ohm video load 58, 59.

The 3.56 mc. tuned circuit 60, 61 isolates the reference signal from thegrids of twin amplifier 63, preventing biasing due to rectification.

The .25 mfd. capacitors 64, 65 block the direct current rectified by thediodes '55, 56 and prevent biasing of video amplifiers 63.

While the direct current component of the demodulated video signals isthereby removed from the output of amplifiers 63, it has been found thata sufliciently long time constant permits little loss of the significantchroma information.

In other respects the output circuit of, video amplifiers 63 resemblesthat of Fig. 5.

The invention is not limited to the, tubes and tube elements shown anddescribed nor to the. circuits and circuit elements shown and describedbut can be applied in any form or manner whatsoever without departingfrom the scope of this disclosure. Y

I claim:

1. In combination, a number of juxtaposed phosphor elements ofalternatingly diflerent primary color reproduction, an aperture mask inalignment therewith, means for directing an electron beam through saidaperture mask to impinge upon said phosphor elements'in the form of ashadow extending over the width of at least one of said elements, meansfor deflecting said electron beam under control of synchronizing pulsesto provide a display raster on said elements, means for displacing the,axis or said electron beam under control of composite color informationpulses so as to produce a displaced beam having an axis intersecting theaxis of said beam when in rest position at said aperture mask, therebycausing said shadow to be shared simultaneously by adjacent primarycolor elements to reproduce said composite color, said displacing meansincluding electrostatic deflecting means and a beam deflectiondemodulating tube, said demodulating tube having a pair of anodescontrolling said. deflecting means, a control electrode under control ofthe undemodulated chrome signal and a pair of deflection electrodesunder control of local reference signals. 7

2. In combination, a number of juxtaposed phosphor elements ofalternatingly difierent primary color reproduction, an aperture mask inalignment therewith, means for directing an electron beam through saidaperture mask to impinge upon said phosphor elements in the form of ashadow extending over the width of at least one of said elements, meansfor deflecting said electron beam under control of synchronizing pulsesto provide a display raster on said elements, means for displacing theaxis of said electron beam under control of composite color informationpulses so as to produce a displaced beam having an axis intersecting theaxis of said beam when in rest position at said aperture mask, therebycausing said shadow to bev shared simultaneously by adjacent primarycolor elements to reproduce said composite color, said displacing meansincluding a pair of demodulating diodes under control of theundemodulatedi chrome input, a pair of separate amplifier meanscontrolled by said diodes, a pair of electrostatic plates controlled bysaid amplifier means, and input means under control of local referencesignals being inserted between said diodes and said amplifier means toapply synchronous signals in opposite phase relationship.

(References on followingfpage) References Cited in the file of thispatent Re. 23,838 Re. 23,964 2,307,188 2,663,757 2,672,575 2,679,614

UNITED STATES PATENTS Rajchman June 8, 1954 Jenny Mar. 22, 1955 BedfordJan. 5, 1943 Lubcke Dec. 22, 1953 Werenfels Mar. 16, 1954 Friend May 25,1954 Fyler Sept. 28, 1954 Law Dec. 7, 1954 Skellett June 14, 1955Lawrence June 21, 1955 Scull Dec. 20, 1955 Moore Dec. 4, 1956 BenwayFeb. 19, 1957 Jurgens Aug. 20, 1957

